1. Field of the Invention
This invention is related to a reaction/regeneration apparatus, and particularly is related to continuous separation of contaminants and regeneration of adsorbent or is related to the carrying out of chemical reactions and the regenerating of catalyst continuously in the stationary radial flow beds.
2. Description of the Prior Art
The term reaction herein includes both the physical and chemical adsorption and chemical reaction processes. The adsorption process is widely used for the component separation in many industries. The adsorption is typically a batch type process. The desirable product can only be produced part of the time and the adsorbent bed needs to be regenerated. To provide a continuous flow of desirable product, it is often necessary to use multiple vertical vessels having fluid flows axially through the vertical beds. A series of the steps, including adsorption, purging and regeneration are carried out in each vessel. Fluid with non-adsorbed components is produced during the adsorption step and the components adsorbed are recovered during desorption or regeneration step. The regeneration is typically achieved by either process pressure reduction in pressure swing adsorption (PSA) or by raising process temperature in temperature swing adsorption (TSA). Depending on if a PSA or TSA process is used, additional steps such as equalization or cooling are needed.
To properly direct the flow to and from each vessel during the cycling of steps, conventionally, it is necessary that multiple lines are used in a multi-vessel adsorption system with valves open and close at different times. The valves can be cycled as short as every minute in a PSA system which can lead to high wear of valves. Alternately, a rotary flow distribution assembly or valve is used in U.S. Pat. Nos. 4,935,464, 5,268,021, 5,366,541, 5,779,771, 5,820,656, 6,457,485. A typical rotary valve includes a valve port disk and a rotary valve. The rotary valve is rotated relative to stationary valve port disk so that the openings of the rotary valve register with the holes in the valve port disk. This enables appropriate fluids to flow to and from the different vessels during the various steps of the cycle. Different inventors invented different rotary valve designs and multiple vessels are used. With the rotary valve, many of the automatic valves in the conventional multi-vessels adsorption system can be eliminated. However, multiple vessels with many connecting lines between the valve and vessels are still needed. U.S. Pat. No. 5,779,771 uses a rotary flow distributor assembly to distribute two feeds, namely, decontamination and regeneration fluids, to several individual container vessels. The rotary flow distributor disclosed can distribute only two fluids alternately which limits the applicability of the assembly. Due to the limitation of only two feeds and no purging fluid can be used, the mixing of the two fluids in the containers or vessels can not be avoided during the switching of fluid in the vessel. Instead of using a rotary valve to change the flow, U.S. Pat. Nos. 4,589,892, 5,464,468, 5,441,559, 6,447,583 and 6,783,738 rotate the packed solid adsorbent beds. The adsorption and regeneration are performed sequentially in the rotating adsorbent beds with the stationary inlet and outlet ports which are connected to the fixed gas distribution chambers. The rotation of the heavy adsorbent beds can have high torque requirement and require a large motor.
As shown in the previous references, most of the efforts in the prior art are made to improve the rotary valve design or to improve the rotating adsorbent beds. The rotary valve still requires many inlet outlet lines to communicate feeds and effluents with the different vessels or adsorbent beds. The rotating adsorbent bed needs high torque and requires a large motor. Most of the processes are typically operated in steps rather than continuously. The adsorption performance in discrete time step is similar to the performance of the batch operation. The performance declines and the adsorbate in the product increases when the adsorbent reaches the adsorbate breakthrough point. For the temperature swing adsorption, the process effluent temperatures can cycle with time. The longitudinal flow path of the cylindrical adsorbent bed is used typically in most systems and is known to have higher pressure losses than a radial flow system. U.S. Pat. Nos. 5,133,784, 5,597,489, 6,086,659, and US 2006/0236867 and WO 86/06056 discuss the radial flow adsorption in the multiple vessel or rotating bed. U.S. Pat. Nos. 6,751,964 and 7,338,548 disclose the state of art air desiccant dehumidifier employing a parallel passage way rotating desiccant wheel rotor. The rotating desiccant wheel required the special manufacturing technique to impregnate the active desiccant to alternate layers of flat and corrugated sheets.
The chemical reaction processes are used to convert the low value reactants into high value useful products. The fixed bed reactor loaded with catalyst to promote the reactions is widely used in the chemical, petrochemical and petroleum industries. The catalyst used in the reactor can become deactivated for one or more reasons. The most common reason for the deactivation is the accumulation of coke on the catalyst. To restore the performance of the deactivating catalyst, careful burning of the accumulated coke is frequently performed. The catalyst is reactivated by contacting of the coke containing catalyst at high temperature with an oxygen containing gas. The coke combustion is carried out in the same fixed bed periodically or the catalyst with coke in the reactor is transferred from the reactor to a regenerator to burn off the coke. U.S. Pat. No. 3,652,231 shows a regeneration apparatus for a continuous catalyst regeneration process. This regeneration apparatus is used in the catalytic reforming of hydrocarbons with a moving bed catalyst. U.S. Pat. Nos. 3,647,680 and 3,692,496 also deal with regeneration of reforming catalyst. To remove the coke on the deactivated catalyst, the reactor must be shut down periodically for the fixed bed reactor system or an additional regenerator system is needed for the moving bed system.
Therefore it is an object of this invention to provide a reaction apparatus capable of performing adsorption or chemical reaction and regeneration continuously in a single vessel without the need to shut down the process for regeneration.